The SNR for a given system drops as a function of the reach or the distance between the transmit (or source) site and the receive (or sink) site. The practical consequence of this is that, if a specific bit error rate (BER) is desired, the reach of the system (i.e., the maximum reliable transmission distance between the source site and the sink site) becomes limited by the signal-to-noise ratio (SNR) of the bins used to carry the information (or data). Generally, in a digital subscriber line (DSL) system employing digital multi-tone (DMT) to transmit information, the system determines the SNR associated with each bin to determine whether each bin has sufficient capacity for data transmission. The SNR is derived as a function of the distance (or reach) and frequency, the desired BER, the type of data modulation, etc. Once the system determines which bins have sufficient SNR (hereinafter referred to as “sufficient-SNR bins”) and which bins have insufficient SNR (hereinafter referred to as “insufficient-SNR bins”), the system usually allocates data to only those bins having a sufficient SNR to satisfy the BER requirement over a given distance. As a practical consequence of only loading sufficient-SNR bins with data, the insufficient-SNR bins are transmitted as “unloaded” bins (i.e., transmitted without data). Hence, generally, as the loop length (or reach) increases, the number of unloaded bins increases due to the SNR-per-bin limitation. In other words, for such a system, either the reach is limited by the bin SNR or the number of loaded bins is limited by the bin SNR. The SNR limitation causes inefficiencies in transmission of information from the source site to the sink site.
Due to these limitations, which exist in a DSL-DMT system as well as other types of signal transmission systems, there is a need in the art for a system and method of transferring data over a greater reach.